Press for plastic material.



No. 788,120. PATENTED APR. 25, 1905. G. W. THOMAS.

PRESS FOR PLASTIC MATERIAL.

APPLICATION FILED JULY 21, 1904.

2 SHEETS-SHEET 1:

A z I E I WITNESSES l i g M55423:

MM Um ATTORNEYS PATENTED APR. 25, 1905.

G. W. THOMAS.

PRESS FOR PLASTIC MATERIAL.

APPLICATION FILED JULY 21, 1904.

2 BHEETSSHEET 2.

INVENTUR W am WITNESSES ATTORNEYS Patented April 25, 1905.

NITED STATES PATENT OFFICE.

GEORGE IV. THOMAS, OF EAST LIVERPOOL, OHIO, ASSIGNOR TO THE It.

THOMAS AND SONS COMPANY, OF EAST LIVERPOOL, OHIO, A COR- PORATION OFOHIO.

PRESS FOR PLASTIC MATERIAL.

SPECIFICATION forming part of Letters Patent No. 788,120, dated. April25, 1905.

Application filed July 21,1904. Serial No. 217,556.

To all whom it may concern.-

Be it known that I, GEORGE IV. THOMAS, a citizen of the United States ofAmerica, residing in East Liverpool, in the county of Columbiana, Stateof Ohio, have invented an Improved Press for Plastic Material, of whichthe following is a specification.

My invention relates to presses constructed for operating on clay andlike plastic material, and more particularly to presses for forming clayinto proper shapes for the production of porcelain insulators in whichhell or cup shaped parts are molded with threads in the bottom of thebell or cup for the reception of the threaded supporting-pins.

The object of my invention is to so construct the apparatus as tofacilitate and simplify the work and to improve the product.

In the accompanying drawings, Figure 1 is a side elevation, partly insection, of the complete press with the parts in the positions where theforming-mandrel is about to be pressed into the clay in the mold. Fig. 2is a view, on an enlarged scale, partly in section and showing the moldand mandrel parts; and Fig. 3 is a still larger view, partly in section,of the two-part mandrel.

The frame of the press may be of any suitable construction. In thedrawings l have shown it as comprising a base A with a supporting-pillarB, which carries two verticallyadj List-able guide-arms C and O. In theouter ends of these arms is guided the plungerspindle D, which carriesat its lower end the forming-mandrel and has connected to its upper enda suitable counterweight \V. A rack F on the spindle has geared to it apinion f on a shaft provided with a hand-wheel E, by turning which thespindle may be depressed to force the mandrel into the plastic clay inthe mold (1. This mold is preferably made of plaster and is mounted upona table or twirler which can be conveniently rotated in the base A, sucha twirler as is in common use in potteries, except that this twirler hasan annular flange t to support and hold the mold.

An important feature of my invention consists in the construction of themandrel to form or shape the inside of the insulator-bell 5 or othercup-shaped piece. I make this mandrel in two separable partsone, J, thenonrotating body portion, and the other, K, the threaded terminalportion, separable from the body portion in the press. The body-piece Jis to be secured by clamping-screws or otherwise to the lower end of theplunger-spindle D, Fig. 1, and has a central vertical opening from thebottom to near its top for the reception of the hollow spindle it of thethreaded 6o portion K of themandrel, Fig. 2. This openingj has anair-inletj at the top of the mandrel J, and the hollow interior of thespindle 7U communicates with a small air-passage l:

to the extreme outer end of the threaded mandrel K, Fig. 2. Inconnection with this threaded portion of the mandrel I employ a disk m,Fig. 2, of paper or like combustible material, and in connection withthe body portion J, I employ a tubular jacket 11, Fig. 3, of wovenfabric, such as cotton or linen, shaped to tit over the tapering wallsof the mandrel, which would otherwise come into contact with the clay.This fabric jacket is of such length that when the mandrel has beendepressed to its proper position within the mold the upper margin of thefabric jacket will be open to the air at the mouth of the mold, so thatair has then access to the upper part of the fabric jacket between themandrel and the clay, and consequently the moment the mandrel starts towithdraw the air can enter, permitting easy withdrawal of the mandrel.

In using the described construction the operator first places in theplaster mold a proper quantity of a clay, as indicated at X, Fig. 1.Then placing the jacket a on the mandrel J and the detachable threadedmandrel-piece K into the mandrel J and providing a paper disk m. toclose the outer end of the air-passage k 9 the spindle D and two-partmandrel are forced downward into the clay'in the mold without rotation.Then the spindle D is raised without rotation, carrying with it theattached part J of the mandrel, but leaving behind both the fabricjacket n and the threaded part K of the mandrel. The presence of thefabric permits the body portion of the mandrel to easily withdraw fromthe mold ed clay, for the fabric permits air to enter as the mandrelstarts to withdraw. The operator then picks the fabric jacket out of themolded clay, and then taking the spindlek of the threaded mandrel in onehand he turns the twirler-table T, whose axis of rotation is the same asthat of the threaded mandrel, with the other hand in a proper directionto screw the threaded mandrel K out of the molded clay, the air-ventpermitting this. The paper disk which acted as a valve to close thisair-vent during the pressing operation may be left in the clay cup to beburned in the kiln, or it may be picked out, if convenient.

The attached conical valves commonly employed in the ends ofscrew-mandrels have the objection that they are liable to choke up andfail to work properly, so that on withdrawing such screw-mandrel fromthe clay suction on the latter produces defects which in a finishedproduct of the character of a high-tension insulator are of the mostserious importance. The loose or separable disk valve which I employavoids this difliculty entirely.

The usual practice in molding insulatorpieces has been to screw thewhole mandrel into and out of the clay; but I have found that thisrotary motion of the mandrel has an injurious action upon the structureof the clay. This I have avoided by making the main body of the mandrelnon-rotating, as described.

I claim as my invention- 1. A press for plastic material, comprising amold and a mandrel having a fabric jacket whose upper margin is open tothe mouth of the mold when the mandrel has been pressed into the mold,whereby the withdrawalof the mandrel from the moldis facilitated.

2. A press for plastic material, comprising a plaster mold incombination with a mandrel having a fabric jacket whose upper margin isopen to the mouth of the mold when the mandrel has been pressed into themold, whereby the withdrawal of the mandrel from the mold isfacilitated.

3. A press for plastic material, comprising a mold, in combination witha mandrel in two parts, a body portion and a terminal threaded portionseparable from each other in the press, and a fabric jacket for the bodyportion adapted to facilitate the withdrawal of said body portion fromthe mold.

a. A press for plastic material, comprising a mold, in combination witha mandrel in two parts, consisting of a body portion having an air-ventand a terminal threaded portion also with an air-vent and separable fromthe body portion in the press.

5. A press for plastic material, comprising a mold in combination with amandrel, having an air-vent and a separate disk detached from themandrel to close the air-vent during the pressing operation.

6. A press for plastic material, comprising a mold, in combination witha mandrel having an air-vent and a disk of combustible material to closethe air-vent during the pressing operation.

7 A press for plastic material, comprising a mold and a supportingtwirler-table therefor, in combination with a mandrel having ascrew-threaded part, the axis of rotation of the twirler and thescrew-threaded part being the same, whereby withdrawal of thescrewthreaded part from the mold is facilitated.

8. A press for plastic material, comprising a mold and a supportingtwirler-table therefor in combination with a mandrel in two parts, one abody portion and the othera terminal threaded portion separable from thebody portion in the press, the axis of rotation of the twirler and theterminal threaded portion being the same, whereby withdrawal of saidthreaded terminal portion is faciltated.

9. A press for plastic material, comprising a mold in combination with amandrel in two parts, consisting of a non-rotating body portion having afabric jacket adapted to facilitate the withdrawal of the said bodyportion from the mold, and a terminal threaded portion separable fromthe body portion in the press.

10. A press for plastic material, comprising a plaster mold incombination with a mandrel in two parts, consisting of a body portionhaving a fabric jacket for the purpose set forth, and a terminalthreaded portion separable from the body portion in the press.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

GEORGE W. THOMAS.

Witnesses:

H. R. I-IoLMEs, B. D. KENNEY.

